Luke A J O'Neill

Trinity College Dublin, Dublin, Leinster, Ireland

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Publications (293)2598.76 Total impact

  • Beth Kelly · Gillian M Tannahill · Michael P Murphy · Luke A J O'Neill
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    ABSTRACT: Metformin, a frontline treatment for Type II Diabetes Mellitus (T2DM)(3), decreases production of the pro-form of the inflammatory cytokine interleukin (IL)-1β in response to lipopolysaccharide (LPS) in macrophages. We have found that it specifically inhibited pro-IL-1β production, having no effect on tumour necrosis factor-α (TNF-α). Furthermore, metformin boosted induction of the anti-inflammatory cytokine IL-10 in response to LPS. We ruled out a role for AMP-activated protein kinase (AMPK) in the effect of metformin, since activation of AMPK with A769662 did not mimic metformin here. Furthermore, metformin was still inhibitory in AMKPα1- or AMPKβ1-deficient cells. The activity of NADH:ubiquinone oxidoreductase (complex I) was inhibited by metformin. Another complex I inhibitor, rotenone, mimicked the effect of metformin on pro-IL-1β and IL-10. LPS induced reactive oxygen species (ROS) production, an effect inhibited by metformin or rotenone pretreatment. MitoQ, a mitochondria-targeted antioxidant, decreased LPS-induced IL-1β without affecting TNF-α. These results therefore implicate complex I in LPS action in macrophages. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 07/2015; 290(33). DOI:10.1074/jbc.M115.662114 · 4.57 Impact Factor
  • Mihai G Netea · Eicke Latz · Kingston H G Mills · Luke A J O'Neill
    Nature Immunology 06/2015; 16(7):675-9. DOI:10.1038/ni.3178 · 20.00 Impact Factor
  • Deepthi Menon · Rebecca Coll · Luke A J O'Neill · Philip G Board
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    ABSTRACT: Macrophages mediate innate immune responses that recognise foreign pathogens, and bacterial lipopolysaccharide (LPS) recruits a signalling pathway through Toll-like receptor 4 (TLR4) to induce pro-inflammatory cytokines and reactive oxygen species (ROS). LPS activation also skews the metabolism of macrophages towards a glycolytic phenotype. Here, we demonstrate that the LPS-triggered glycolytic switch is significantly attenuated in macrophages deficient for glutathione transferase omega-1 (GSTO1, note that GSTO1-1 refers to the dimeric molecule with identical type 1 subunits). In response to LPS, GSTO1-1-deficient macrophages do not produce excess lactate, or dephosphorylate AMPK, a key metabolic stress regulator. In addition, GSTO1-1-deficient cells do not induce HIF1α, which plays a key role in maintaining the pro-inflammatory state of activated macrophages. The accumulation of the TCA cycle intermediates succinate and fumarate that occurs in LPS-treated macrophages was also blocked in GSTO1-1-deficient cells. These data indicate that GSTO1-1 is required for LPS-mediated signalling in macrophages and that it acts early in the LPS–TLR4 pro-inflammatory pathway.
    Journal of Cell Science 05/2015; 128(10). DOI:10.1242/jcs.167858 · 5.43 Impact Factor
  • Moritz Haneklaus · Luke A J O'Neill
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    ABSTRACT: The discovery of the NLRP3 (NLR family, pyrin domain containing 3) inflammasome provided an important molecular mechanism in the induction of the central pro-inflammatory cytokine interleukin-1β (IL-1β), via activation of caspase-1, which processes pro-IL-1β into its mature active form. IL-1 has long been known to exert metabolic effects, most notably being implicated in insulin resistance and obesity. A key phenotype of the NLRP3-deficient mouse is insulin hypersensitivity. Over the past 5 years, a number of discoveries have been made suggesting a close interplay between NLRP3 and metabolism. Metabolic products have been shown to activate NLPR3, and disturbed mitochondria have been shown to be involved in NLRP3 function. It is possible that under normal physiology NLRP3 is homeostatic and maintains the metabolic balance. However, upon chronic activation (e.g. in obesity or hypercholesterolemia), NLRP3 becomes pathologic and promotes disease. Here, we review these findings and place them in the context of exciting new insights that are improving our understanding of the link between inflammation and metabolism. These insights are giving rise to better understanding of disease pathogenesis and might point to new therapeutic approaches. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
    Immunological Reviews 05/2015; 265(1):53-62. DOI:10.1111/imr.12285 · 10.12 Impact Factor
  • Luke A J O'Neill
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    ABSTRACT: Macrophages undergo metabolic rewiring during polarization but details of this process are unclear. In this issue of Immunity, Jha etal. (2015) report a systems approach for unbiased analysis of cellular metabolism that reveals key metabolites and metabolic pathways required for distinct macrophage polarization states. Macrophages undergo metabolic rewiring during polarization but details of this process are unclear. Jha etal. report a systems approach for unbiased analysis of cellular metabolism that reveals key metabolites and metabolic pathways required for distinct macrophage polarization states.
    Immunity 03/2015; 42(3):393-4. DOI:10.1016/j.immuni.2015.02.017 · 21.56 Impact Factor
  • Cell Metabolism 02/2015; 21(2):347-347. DOI:10.1016/j.cmet.2015.01.017 · 17.57 Impact Factor
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    ABSTRACT: Macrophages activated by the TLR4 agonist LPS undergo dramatic changes in their metabolic activity. We here show that LPS induces expression of the key metabolic regulator Pyruvate Kinase M2 (PKM2). Activation of PKM2 using two well-characterized small molecules, DASA-58 and TEPP-46, inhibited LPS-induced Hif-1α and IL-1β, as well as the expression of a range of other Hif-1α-dependent genes. Activation of PKM2 attenuated an LPS-induced proinflammatory M1 macrophage phenotype while promoting traits typical of an M2 macrophage. We show that LPS-induced PKM2 enters into a complex with Hif-1α, which can directly bind to the IL-1β promoter, an event that is inhibited by activation of PKM2. Both compounds inhibited LPS-induced glycolytic reprogramming and succinate production. Finally, activation of PKM2 by TEPP-46 in vivo inhibited LPS and Salmonella typhimurium-induced IL-1β production, while boosting production of IL-10. PKM2 is therefore a critical determinant of macrophage activation by LPS, promoting the inflammatory response. Copyright © 2015 Elsevier Inc. All rights reserved.
    Cell Metabolism 01/2015; 21(2-1):65-80. DOI:10.1016/j.cmet.2014.12.005 · 17.57 Impact Factor
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    ABSTRACT: Activation of the noncanonical inflammasome, mediated by caspase-11, serves as an additional pathway for the production of the proinflammatory cytokines IL-1β and IL-18. Noncanonical inflammasome activity occurs during host defense against Gram-negative bacteria and in models of acute septic shock. We propose that the noncanonical inflammasome is activated in mice during acute intestinal inflammation elicited by dextran sodium sulfate (DSS), a model of experimental colitis. We find that caspase-11(-/-) mice display enhanced susceptibility to DSS, because of impaired IL-18 production. The impaired IL-18 levels observed are shown to result in reduced intestinal epithelial cell proliferation and increased cell death. We also suggest that a novel type II IFN-dependent, type I IFN-TRIF-independent signaling pathway is required for in vivo caspase-11 production in intestinal epithelial cells during DSS colitis. Collectively, these data suggest that IFN-γ-mediated caspase-11 expression has a key role maintaining intestinal epithelial barrier integrity in vivo during experimentally induced acute colitis. Copyright © 2014 The Authors.
    Immunology 12/2014; 143(3). DOI:10.4049/jimmunol.1400501 · 3.80 Impact Factor
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    ABSTRACT: Bordetella pertussis causes whooping cough, an infectious disease of the respiratory tract that is re-emerging despite high vaccine coverage. Here we examined the role of Toll-like receptor (TLR) adapter protein Mal in the control of B. pertussis infection in the lungs. We found that B. pertussis bacterial load in the lungs of Mal-defective (Mal(-/-)) mice exceeded that of wild-type (WT) mice by up to 100-fold and bacteria disseminated to the liver in Mal(-/-) mice and 50% of these mice died from the infection. Macrophages from Mal(-/-) mice were defective in an early burst of pro-inflammatory cytokine production and in their ability to kill or constrain intracellular growth of B. pertussis. Importantly, the B. pertussis bacterial load in the lungs inversely correlated with the number of alveolar macrophages. Despite the maintenance and expansion of other cell populations, alveolar macrophages were completely depleted from the lungs of infected Mal(-/-) mice, but not from infected WT mice. Our findings define for the first time a role for a microbial pattern-recognition pathway in the survival of alveolar macrophages and uncover a mechanism of macrophage-mediated immunity to B. pertussis in which Mal controls intracellular survival and dissemination of bacteria from the lungs.Mucosal Immunology advance online publication, 17 December 2014; doi:10.1038/mi.2014.125.
    Mucosal Immunology 12/2014; 8(5). DOI:10.1038/mi.2014.125 · 7.37 Impact Factor
  • Luke A J O'Neill
    Nature 11/2014; 515(7527). DOI:10.1038/nature13941 · 41.46 Impact Factor
  • 2nd Annual Meeting of the International-Cytokine-and-Interferon-Society; 11/2014
  • L. E. Gleeson · F. Sheedy · S. O'Leary · M. O'Sullivan · L. A. J. O'Neill · J. Keane
    Irish Journal of Medical Science 11/2014; 183:S537-S537. · 0.83 Impact Factor
  • Moritz Haneklaus · Seth L. Masters · Luke A. J. O'Neill
    2nd Annual Meeting of the International-Cytokine-and-Interferon-Society; 11/2014
  • Source
    Silvia Galván-Peña · Luke A J O'Neill
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    ABSTRACT: Studying the metabolism of immune cells in recent years has emphasized the tight link existing between the metabolic state and the phenotype of these cells. Macrophages in particular are a good example of this phenomenon. Whether the macrophage obtains its energy through glycolysis or through oxidative metabolism can give rise to different phenotypes. Classically activated or M1 macrophages are key players of the first line of defense against bacterial infections and are known to obtain energy through glycolysis. Alternatively activated or M2 macrophages on the other hand are involved in tissue repair and wound healing and use oxidative metabolism to fuel their longer-term functions. Metabolic intermediates, however, are not just a source of energy but can be directly implicated in a particular macrophage phenotype. In M1 macrophages, the Krebs cycle intermediate succinate regulates HIF1α, which is responsible for driving the sustained production of the pro-inflammatory cytokine IL1β. In M2 macrophages, the sedoheptulose kinase carbohydrate kinase-like protein is critical for regulating the pentose phosphate pathway. The potential to target these events and impact on disease is an exciting prospect.
    Frontiers in Immunology 09/2014; 5:420. DOI:10.3389/fimmu.2014.00420
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    ABSTRACT: TLR4 interactor with leucine-rich repeats (TRIL) is a brain-enriched accessory protein that is important in TLR3 and TLR4 signaling. In this study, we generated Tril(-/-) mice and examined TLR responses in vitro and in vivo. We found a role for TRIL in both TLR4 and TLR3 signaling in mixed glial cells, consistent with the high level of expression of TRIL in these cells. We also found that TRIL is a modulator of the innate immune response to LPS challenge and Escherichia coli infection in vivo. Tril(-/-) mice produce lower levels of multiple proinflammatory cytokines and chemokines specifically within the brain after E. coli and LPS challenge. Collectively, these data uncover TRIL as a mediator of innate immune responses within the brain, where it enhances neuronal cytokine responses to infection.
    The Journal of Immunology 07/2014; 193(4). DOI:10.4049/jimmunol.1302392 · 4.92 Impact Factor
  • Susan R Quinn · Luke A O'Neill
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    ABSTRACT: Recent studies have shown an important interplay between Interleukin 10 (IL-10) and microRNAs. IL-10 can be directly post-transcriptionally regulated by several microRNA, including miR-106a, miR-4661, miR-98, miR-27, let7 and miR-1423p/5p. miRNA targeting of IL-10 has been suggested to play a role in autoimmune and inflammatory diseases such as SLE, reperfusion injury and asthma. Another miRNA, miR-21, has been shown to indirectly regulate IL-10 via downregulation of the IL-10 inhibitor PDCD4. The targeting of IL-10 in this way has been linked to host defence modulation by Mycobacterium leprae. Viral miRNAs, such as miR-K12-3 from Kaposi's sarcoma-associated herpesvirus (KSHV), can also decrease IL-10 to promote tumour development. Finally this interplay can operate in a feedback loop, with IL-10 capable of regulating microRNAs, upregulating those that can contribute to exerting the anti-inflammatory response, such as miR-187, and downregulating those that are highly pro-inflammatory, such as miR-155. Understanding the two-way regulation between miRNA and IL-10 is giving rise to new insights into this important cytokine.
    Current topics in microbiology and immunology 07/2014; 380:145-55. DOI:10.1007/978-3-662-43492-5_7 · 4.10 Impact Factor
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    ABSTRACT: Programmed cell death protein 4 (PDCD4) is a tumor suppressor and has also been shown to suppress production of the immunomodulatory cytokine IL-10. The precise role of PDCD4 in IL-10 induction in macrophages is still not fully understood. Incubation of macrophages with inhibitors of PI3K and mTOR blocked LPS-stimulated PDCD4 degradation and expression of c-Maf and IL-10 production. PDCD4 and the transcription factor Twist2 were shown to form a complex in untreated cells. LPS disrupted the complex allowing Twist2 to bind to the c-Maf promoter. PI3K and mTOR inhibitors prevented this disruption by stabilizing PDCD4 and thereby decreased Twist2 binding to the c-Maf promoter and induction of c-Maf mRNA. These results indicate a regulatory role for PDCD4 and Twist2 in LPS-induced IL-10 production in macrophages. LPS promotes PDCD4 degradation via a pathway involving PI3K and mTOR, releasing Twist2, which induces IL-10 via c-Maf.
    Journal of Biological Chemistry 06/2014; 289(33). DOI:10.1074/jbc.M114.573089 · 4.57 Impact Factor
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    ABSTRACT: The prognosis of epithelial ovarian cancer is poor in part due to the high frequency of chemoresistance. Recent evidence points to the Toll-like receptor-4 (TLR4), and particularly its adaptor protein MyD88, as one potential mediator of this resistance. This study aims to provide further evidence that MyD88 positive cancer cells are clinically significant, stem-like and reproducibly detectable for the purposes of prognostic stratification. Expression of TLR4 and MyD88 was assessed immunohistochemically in 198 paraffin-embedded ovarian tissues and in an embryonal carcinoma model of cancer stemness. In parallel, expression of TLR4 and MyD88 mRNA and regulatory microRNAs (miR-21 and miR-146a) was assessed, as well as in a series of chemosensitive and resistant cancer cells lines. Functional analysis of the pathway was assessed in chemoresistant SKOV-3 ovarian cancer cells. TLR4 and MyD88 expression can be reproducibly assessed via immunohistochemistry using a semi-quantitative scoring system. TLR4 expression was present in all ovarian epithelium (normal and neoplastic), whereas MyD88 was restricted to neoplastic cells, independent of tumour grade and associated with reduced progression-free and overall survival, in an immunohistological specific subset of serous carcinomas, p<0.05. MiR-21 and miR-146a expression was significantly increased in MyD88 negative cancers (p<0.05), indicating their participation in regulation. Significant alterations in MyD88 mRNA expression were observed between chemosensitive and chemoresistant cells and tissue. Knockdown of TLR4 in SKOV-3 ovarian cells recovered chemosensitivity. Knockdown of MyD88 alone did not. MyD88 expression was down-regulated in differentiated embryonal carcinoma (NTera2) cells, supporting the MyD88+ cancer stem cell hypothesis. Our findings demonstrate that expression of MyD88 is associated with significantly reduced patient survival and altered microRNA levels and suggest an intact/functioning TLR4/MyD88 pathway is required for acquisition of the chemoresistant phenotype. Ex vivo manipulation of ovarian cancer stem cell (CSC) differentiation can decrease MyD88 expression, providing a potentially valuable CSC model for ovarian cancer.
    PLoS ONE 06/2014; 9(6):e100816. DOI:10.1371/journal.pone.0100816 · 3.23 Impact Factor
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    ABSTRACT: Background Giant cell arteritis (GCA) is a common form of primary vasculitis characterised by dysfunctional vessels and inflammatory infiltration leading to luminal occlusion. It is now evident that these processes may be altered by a class of small non-coding RNAs or microRNA (miRNA), which exert their biological function through suppression of specific target genes. Abnormal miRNA expression has been demonstrated in cancer and chronic inflammatory arthritis, however to date miRNA have not been examined in GCA. Objectives This study examines expression and regulation of miRNA in GCA. Methods Temporal artery (TA) sections from patients positive and negative for GCA were assessed by immunohistology. Peripheral blood mononuclear cells (PBMC) from GCA positive (n=10), GCA negative (n=2) and healthy controls (n=4) were collected and expression of miR-155, miR-146a, miR-125a-3p/-5p and miR-323-3p were quantified using the Qiagen miRNA isolation kit (Qiagen) and Taqman PCR. To examine possible factors involved in regulating miRNA expression, GCA positive PBMC were cultured with candidate stimuli including Toll-like receptor (TLR) ligands- Pam3CSK4 (1 ng/ml), LPS (100 ng/ml) and pro-inflammatory cytokines- IL-1β (1 ng/ml) and TNFα (10 ng/ml). Total RNA was isolated and individual miRNA quantified by Taqman assay. In parallel IL-6, IL-8 and IL-10 were quantified in cultured supernatants by ELISA. Results Increased miR-155 levels were demonstrated in GCA positive PBMC compared to healthy controls and GCA negative PBMC (p<0.05). No difference in expression of miR-125a-5p or miR-146a was observed. MiR-323-3p and miR-125a-3p were undetectable in all samples. Pam3CSK4 and IL-1β significantly induced miR-155 and miR-146 (p<0.05), while TNFα induced miR-146a expression (P<0.05) with no effect observed for LPS. In parallel, Pam3CSK4 and/or IL-1β significantly induced IL-6, IL-8 and IL-10 protein expression. Finally in silico analysis was used to identify putative microRNA targets which included IL-6R, IL-6 gp130 and TRAF3. Conclusions This study demonstrates for the first time increased expression and regulation of miRNA in patients positively diagnosed for GCA suggesting potential therapeutic regulation for the treatment of GCA. Disclosure of Interest S. Wade: None declared, M. Connolly: None declared, L. O'Neill: None declared, J. Mc Cormick: None declared, D. Veale Grant/research support: Abbvie,MSD,Pfizer,Roche, Consultant for: Pfizer,Roche, Speakers bureau: Abbott, MSD,Pfzier, Roche, C. Murphy: None declared, E. Molloy: None declared, U. Fearon: None declared DOI 10.1136/annrheumdis-2014-eular.5559
    Annals of the Rheumatic Diseases 06/2014; 73(Suppl 2):698-698. DOI:10.1136/annrheumdis-2014-eular.5559 · 10.38 Impact Factor
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    ABSTRACT: Background Systemic Lupus Erythematosus (SLE) involves complex interactions between the innate and adaptive immune systems. Monocytes are increasingly recognised to play a key role in the dysregulated immune response seen in SLE whilst more recently B Lymphocyte Stimulator (BLyS) has been demonstrated to play a key role in the pathogenesis of SLE. Despite the fact that monocytes are one of the key producers of BLyS, the effect of BLyS on monocyte activation in SLE patients has not been determined. Objectives To characterise the activation state of SLE monocytes in their resting state and in response to BLyS. Methods Activation of CD14+ monocytes was characterised in the resting state and following BLyS stimulation in both healthy controls and SLE patients by flow cytometry. Both antigen presenting capacity and co-stimulatory molecule expression were assessed using the following surface markers: CD80, CD86 and HLA-DR. Differences in activation states between groups were examined using the Mann Whitney whilst within group analysis was performed using the Wilcoxon signed-rank test. Spearman's correlation coefficient was also used to assess the relationship between HLA-DR expression and CD80/CD86. Results 25 SLE Patients (as per ACR diagnostic criteria) were recruited. Basal expression of CD80 and HLA-DR was increased on patient monocytes compared to controls (CD80 6.35% v 1.5%, p=0.036, HLA-DR 61.65% v 47.30%, p=0.048). No relationship was observed between disease activity as per SLEDAI and resting SLE patient monocyte function. Interestingly despite their baseline hyper-activated state, following stimulation with BLyS, SLE patients significantly upregulated CD80, CD86 and HLA-DR expression [(CD80 6.35% v 8.4%, p=0.007, CD86 80.8% v 84.6%, p=0.03, HLA-DR 61.65% v 74.95%, p=0.001). In contrast the healthy control volunteers failed to significantly upregulate any of the surface markers following BLyS stimulation indicating that SLE patients monocytes are more responsive to the effects of BLyS. In support of this SLE patients expressed more CD80 and HLA-DR following stimulation than controls (CD 80 8.4% v 2.5%, p=0.0031, HLA-DR 74.95% v 52.90%, p=0.018). When the relationship between CD80/CD86 and HLA-DR surface expression was examined no significant correlation was observed between them in the resting state. However following BLyS stimulation a strong correlation was seen between both CD80/CD86 and HLA-DR expression in SLE patients (CD80 vs HLA-DR:Spearman r =0.64, p=0.005, CD86 vs HLA-DR: Spearman r =0.60, p=0.012) Conclusions Our results suggest that SLE patient monocytes have a hyperactivated phenotype which consequentially results in an enhanced response to BLyS exposure compared to healthy control monocytes. As BLyS plays a significant role in monocyte function in SLE this finding warrants further investigation. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.2174
    Annals of the Rheumatic Diseases 06/2014; 73(Suppl 2):860-860. DOI:10.1136/annrheumdis-2014-eular.2174 · 10.38 Impact Factor

Publication Stats

22k Citations
2,598.76 Total Impact Points


  • 1992–2015
    • Trinity College Dublin
      • • School of Biochemistry and Immunology
      • • Biochemistry
      Dublin, Leinster, Ireland
  • 2014
    • St. Vincent Hospital
      Green Bay, Wisconsin, United States
  • 2012
    • University of North Carolina at Chapel Hill
      • Department of Microbiology and Immunology
      North Carolina, United States
  • 2011
    • University of Cambridge
      • Department of Biochemistry
      Cambridge, ENG, United Kingdom
  • 1995–2011
    • St. James's Hospital
      Dublin, Leinster, Ireland
  • 1995–2008
    • Trinity College
      • • Biochemistry
      • • Psychology
      Hartford, Connecticut, United States
  • 2003
    • Universität Ulm
      Ulm, Baden-Württemberg, Germany
    • University of Bath
      • Department of Pharmacy and Pharmacology
      Bath, ENG, United Kingdom
  • 2001
    • The University of Sheffield
      Sheffield, England, United Kingdom
  • 1993–1999
    • Dublin City University
      • School of Biotechnology
      Dublin, Leinster, Ireland